Semiconductor devices having an electronic amplifier are widely used for voltage regulation. For example, a low drop-out (LDO) regulator, which includes an error amplifier, can be used in a system-on-chip (SOC) or a memory system for power management. Hereinafter, a device or circuit having an electronic amplifier is also referred to as an amplifier circuit.
An amplifier circuit may have a property called a “pole”, which can be deduced from a transfer function of the amplifier circuit. Some amplifier circuits, such as the LDO regulator or a unity gain buffer, have at least one pole, such as an output pole at the output stage of the amplifier circuit. To realize stable operation, the output pole should be compensated. The location, i.e., the frequency, of the output pole depends on a load current of the amplifier circuit. Generally, the load current of the amplifier circuit can vary over a wide range due to, for example, change of the load, and thus the output pole may shift when the load changes. As a result, compensation for the output pole at a certain load may not work well for a different load.